1. Field of the Invention
The present invention relates to nozzles and fluidic circuits for generating a controlled spray pattern.
2. Discussion of the Prior Art
Fluidic inserts or oscillators are well known for their ability to provide a wide range of distinctive liquid sprays. The distinctiveness of these sprays is due to the fact that they oscillate, as compared to the relatively steady state flows or streams emitted from standard spray nozzles.
For ease of construction, fluidic oscillators or inserts are generally manufactured as thin, rectangular members that are molded or fabricated from plastic so as to have specially-designed liquid flow channels fabricated into either their broader top or bottom surfaces. They are typically inserted into the cavity of a housing whose inner walls are configured to form a liquid-tight seal around the insert's boundary surface which contains the specially-designed flow channels. Pressurized liquid enters such an insert and is sprayed from it. However, it should be noted that fluidic oscillators can be constructed so that their liquid flow channels are placed practically anywhere (e.g., on a plane that passes through the member's center) within the member's body: in such instances the fluidic would have a clearly defined channel inlet and outlet.
There are many well known designs of fluidic circuits that are suitable for use with such fluidic inserts. Many of these have some common features, including: (a) at least one power nozzle configured to accelerate the movement of the liquid that flows under pressure through the insert, (b) an interaction chamber through which the liquid flows to initiate flow phenomena and cause spray oscillation, (c) a liquid inlet, (d) a pathway that connects the inlet and the outlet(s) or power nozzle(s), and (e) the outlet throat from which the liquid sprays.
Fluidic circuits have been incorporated into a variety of nozzle assemblies and sprayers for various applications. For example, U.S. Pat. No. 5,749,525, U.S. Pat. RE38013, U.S. Pat. No. 4,508,267 and U.S. Pat. No. 4,443,904 illustrate the state of the art and are incorporated herein by reference for enablement purposes, illustrating the level of skill in the art, broadly speaking.
U.S. Pat. No. 5,749,525 (Stouffer) discloses a fluidic oscillator for vehicle windshield washer systems in which a housing, which can be commonly used on different vehicles, incorporates a fluidic oscillator element, hereinafter termed a “fluidic insert”, which carries a physical silhouette or pattern of a fluidic oscillator and is adapted to create different deflection angles. As used herein, the term “deflection angle” means the angle that the jet of wash liquid makes as it exits the outlet in a plane orthogonal to the plane of the silhouette, and the term “fan angle” is the angle made by the jet sweeping back and forth between the boundaries of the outlet in the plane of the silhouette.
Stouffer's U.S. Pat. No. 4,508,267 entitled LIQUID OSCILLATOR DEVICE and Bray, Jr.'s U.S. Pat. No. 4,463,904 entitled COLD WEATHER FLUIDIC FAN SPRAY DEVICES AND METHOD disclose fluidic oscillators which have been highly successful. They include a housing with a fluidic insert element having the silhouette of a fluidic oscillator, and the insert carried in the housing. The silhouette of the fluidic oscillator typically is of the type disclosed in aforementioned Stouffer U.S. Pat. No. 4,508,267 and Bray, Jr. U.S. Pat. No. 4,463,904, although other forms of fluidic oscillators may be used. This type of fluidic oscillator has a power nozzle issuing a jet of windshield washer liquid into an oscillation chamber towards an outlet which issues the jet of wash liquid into ambient space where it is oscillated to rhythmically sweep back and forth, causing the liquid jet to break up in droplets of predetermined size, configuration or range to impinge on a windshield in a predetermined position under various driving conditions (as disclosed in U.S. Pat. No. 4,157,161). In the Bray, Jr. patent, the Coanda effect wall attachment (or lock-on effect) cause a dwell at the ends of the sweep which tends to make the spray heavier at the ends of the sweep than in the middle. In the Stouffer U.S. Pat. No. 4,508,267, the configuration of the silhouette causes the liquid oscillator to sweep a fan spray with liquid droplets that are relatively uniform throughout the fan spray pattern, and the uniform droplets provide a better cleaning action.
These nozzles devices do not work well under certain conditions, however. For example, cold environments can be challenging, especially if the fluid changes viscosity significantly over the temperature range encountered by the nozzle or sprayer. The prior art nozzles and fluidic circuits will not provide a reliable and effective spray pattern at cold temperatures (e.g., near 0° F.). Fluids or liquids used at such temperatures include alcohol mixtures with water and have low freezing points. Thus, the viscosity of the liquid is high (e.g. 25 cP, where water viscosity at Room Temperature (“RT”) is 1 cP). The prior art fluidic circuits include feedback inducing structural features and those circuits are not satisfactory for many applications, such as headlamp cleaning with a mixture of 50-50 ethanol-water at −4 F, or a squeeze bottle spray with fluid under light pressure.
There is a need, therefore, for an improved cold-fluid tolerant apparatus and method for generating three dimensional or planar sprays in controlled patterns with cold or viscous fluids or liquids.